抄録
Seawater adaptability of chum salmon Oncorhynchus keta fry, weighing 1.5-6.O g, was ex-amined after treatment with thyroxine or thiourea for various periods. Thyroxine or thioureawas administered either orally (250mg L-thyroxine Na salt or 100 mg thiourea/kg diet for 14 days)or by immersion (20mgL-thyroxine or 10g thiourea/100 Iiters for 14 days). The change in plasma Na was followed for 48 h after transfer of the fry to seawater. Although neither thyroxinenor thiourea had any consistent effect on seawater adaptability of the chum salmon fry, thyroxine appears to have effects, if any, on smaller fry.
